Natriuretic polypeptides

ABSTRACT

This document provides methods and materials related to natriuretic polypeptides and the use of natriuretic polypeptides to treat cardiovascular and/or renal conditions. For example, chimeric polypeptides having at least one amino acid segment (e.g., N-terminus tail, ring structure, C-terminus tail, or a combination thereof) of a natriuretic peptide (e.g., ANP, BNP, CNP, URO, or DNP) and an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7)) are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 14/791,047, filed Jul. 2, 2015, which is a continuation of U.S. application Ser. No. 14/003,481, filed Sep. 6, 2013 (now U.S. Pat. No. 9,102,707), which is a National Stage application under 35 U.S.C. §371 of International Application No. PCT/US2012/051734, filed Aug. 21, 2012, which claims the benefit of U.S. Provisional Application Ser. No. 61/648,718, filed May 18, 2012 and U.S. Provisional Application Ser. No. 61/529,113, filed Aug. 30, 2011. The disclosures of the prior applications are considered part of (and are incorporated by reference in) the disclosure of this application.

STATEMENT AS TO FEDERALLY SPONSORED RESEARCH

This invention was made with government support under grant numbers HL036634 and HL076611, awarded by National Institutes of Health. The government has certain rights in the invention.

BACKGROUND

1. Technical Field

This document relates to natriuretic polypeptides. For example, this document provides methods and materials related to natriuretic polypeptides and the use of natriuretic polypeptides to treat cardiovascular and renal conditions.

2. Background Information

Natriuretic polypeptides are polypeptides that can cause natriuresis (increased sodium excretion in the urine). Such polypeptides can be produced by brain, heart, kidney, and/or vascular tissue. The natriuretic peptide family in humans includes the cardiac hormones atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and urodilatin (URO). Natriuretic polypeptides function via guanylyl cyclase receptors (i.e., NPR-A for ANP, BNP, and URO; and NPR-B for CNP) and the second messenger cyclic 3′5′ guanosine monophosphate (cGMP) (Kuhn, Circ. Res., 93:700-709 (2003); Tawaragi et al., Biochem. Biophys. Res. Commun., 175:645-651 (1991); and Komatsu et al., Endocrinol., 129:1104-1106 (1991)).

SUMMARY

This document provides methods and materials related to natriuretic polypeptides and the use of natriuretic polypeptides to treat cardiovascular and/or renal conditions. For example, this document provides chimeric polypeptides having at least one amino acid segment (e.g., N-terminus tail, ring structure, C-terminus tail, or a combination thereof) of a natriuretic peptide (e.g., ANP, BNP, CNP, URO, or Dendroaspis natriuretic peptide (DNP)) and an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7)).

As described herein, a chimeric polypeptide can be designed to include the Ang-(1-7) amino acid sequence attached as the C terminus of the ring structure of CNP in a manner that results in a chimeric polypeptide having the ability to stimulate human cardiac fibroblasts to produce cGMP. These results demonstrate that chimeric polypeptides can be designed to include an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7)) and at least one amino acid segment (e.g., N-terminus tail, tail, or a combination thereof) of a natriuretic peptide (e.g., ANP, BNP, CNP, URO, or Dendroaspis natriuretic peptide (DNP)) in a manner that allows the chimeric polypeptide to exhibit an activity such as the ability to activate cGMP production. In some cases, a chimeric polypeptide provided herein can exhibit a diuretic activity, a natriuretic activity, the ability to activate cGMP, the ability to increase glomerular filtration rate, the ability to reduce renin production, the ability to reduce angiotensin production, the ability to reduce aldosterone production, the ability to reduce abnormally elevated cardiac filling pressures, the ability to optimize renal blood flow, or a combination thereof. In some cases, a chimeric polypeptide provided herein can be a chimeric natriuretic polypeptide.

In general, one aspect of this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:2 or the sequence set forth in SEQ ID NO:2 with no more than three additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:3 or the sequence set forth in SEQ ID NO:3 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can have a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:2. The polypeptide can comprise the sequence set forth in SEQ ID NO:3. The polypeptide can comprise the sequence set forth in SEQ ID NO:1.

In another aspect, this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:4 or the sequence set forth in SEQ ID NO:4 with no more than three additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:5 or the sequence set forth in SEQ ID NO:5 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can have a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:4. The polypeptide can comprise the sequence set forth in SEQ ID NO:5. The polypeptide can comprise the sequence set forth in SEQ ID NO:1.

In another aspect, this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:6 or the sequence set forth in SEQ ID NO:6 with no more than three additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:7 or the sequence set forth in SEQ ID NO:7 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can have a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:6. The polypeptide can comprise the sequence set forth in SEQ ID NO:7. The polypeptide can comprise the sequence set forth in SEQ ID NO:1.

In another aspect, this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:8 or the sequence set forth in SEQ ID NO:8 with no more than three additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:9 or the sequence set forth in SEQ ID NO:9 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can have a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:8. The polypeptide can comprise the sequence set forth in SEQ ID NO:9. The polypeptide can comprise the sequence set forth in SEQ ID NO:1.

In another aspect, this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:10 or the sequence set forth in SEQ ID NO:10 with no more than three additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:11 or the sequence set forth in SEQ ID NO:11 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can have a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:10. The polypeptide can comprise the sequence set forth in SEQ ID NO:11. The polypeptide can comprise the sequence set forth in SEQ ID NO:1.

In another aspect, this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:2 or the sequence set forth in SEQ ID NO:2 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:12 or the sequence set forth in SEQ ID NO:12 with no more than two additions, subtractions, or substitutions. The polypeptide can have a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:2. The polypeptide can comprise the sequence set forth in SEQ ID NO:12.

In another aspect, this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:5 or the sequence set forth in SEQ ID NO:5 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:13 or the sequence set forth in SEQ ID NO:13 with no more than two additions, subtractions, or substitutions. The polypeptide can have a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:5. The polypeptide can comprise the sequence set forth in SEQ ID NO:13.

In another aspect, this document features a polypeptide from 10 to 14 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:12 or the sequence set forth in SEQ ID NO:12 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:12. The polypeptide can lack a ring structure.

In another aspect, this document features a polypeptide from 10 to 16 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:13 or the sequence set forth in SEQ ID NO:13 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:13. The polypeptide can lack a ring structure.

In another aspect, this document features a polypeptide from 19 to 25 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:30 or the sequence set forth in SEQ ID NO:30 with no more than five additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:30. The polypeptide can lack a ring structure.

In another aspect, this document features a polypeptide from 10 to 14 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:12 or the sequence set forth in SEQ ID NO:12 with no more than two additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:12. The polypeptide can lack a ring structure.

In another aspect, this document features a polypeptide from 10 to 16 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:13 or the sequence set forth in SEQ ID NO:13 with no more than two additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:13. The polypeptide can lack a ring structure.

In another aspect, this document features a polypeptide from 19 to 25 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:30 or the sequence set forth in SEQ ID NO:30 with no more than five additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:30. The polypeptide can lack a ring structure.

In another aspect, this document features a polypeptide from 20 to 28 amino acid residues in length. The polypeptide comprises, in an order from amino terminus to carboxy terminus (a) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:7 or the sequence set forth in SEQ ID NO:7 with no more than five additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:7. The polypeptide can lack a C-terminal tail attached to a ring structure.

In another aspect, this document features a polypeptide from 20 to 28 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:36 or the sequence set forth in SEQ ID NO:36 with no more than five additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:36. The polypeptide can lack a N-terminal tail attached to a ring structure.

In another aspect, this document features a polypeptide from 20 to 28 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:36 or the sequence set forth in SEQ ID NO:36 with no more than five additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:36. The polypeptide can lack a C-terminal tail attached to a ring structure.

In another aspect, this document features a polypeptide from 20 to 28 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:7 or the sequence set forth in SEQ ID NO:7 with no more than five additions, subtractions, or substitutions, and (b) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:7. The polypeptide can lack a N-terminal tail attached to a ring structure.

In another aspect, this document features a polypeptide from 17 to 50 amino acid residues in length. The polypeptide comprises, or consists essentially of, in an order from amino terminus to carboxy terminus, (a) the sequence set forth in SEQ ID NO:2, the sequence set forth in SEQ ID NO:4, the sequence set forth in SEQ ID NO:6, the sequence set forth in SEQ ID NO:8, the sequence set forth in SEQ ID NO:10, the sequence set forth in SEQ ID NO:2 with no more than three additions, subtractions, or substitutions, the sequence set forth in SEQ ID NO:4 with no more than three additions, subtractions, or substitutions, the sequence set forth in SEQ ID NO:6 with no more than three additions, subtractions, or substitutions, the sequence set forth in SEQ ID NO:8 with no more than three additions, subtractions, or substitutions, or the sequence set forth in SEQ ID NO:10 with no more than three additions, subtractions, or substitutions, (b) the sequence set forth in SEQ ID NO:3, the sequence set forth in SEQ ID NO:5, the sequence set forth in SEQ ID NO:7, the sequence set forth in SEQ ID NO:9, the sequence set forth in SEQ ID NO:11, the sequence set forth in SEQ ID NO:3 with no more than five additions, subtractions, or substitutions, the sequence set forth in SEQ ID NO:5 with no more than five additions, subtractions, or substitutions, the sequence set forth in SEQ ID NO:7 with no more than five additions, subtractions, or substitutions, the sequence set forth in SEQ ID NO:9 with no more than five additions, subtractions, or substitutions, or the sequence set forth in SEQ ID NO:11 with no more than five additions, subtractions, or substitutions, and (c) the sequence set forth in SEQ ID NO:1 or the sequence set forth in SEQ ID NO:1 with no more than two additions, subtractions, or substitutions. The polypeptide can comprise a cGMP-activating property. The polypeptide can comprise the sequence set forth in SEQ ID NO:2, 4, 6, 8, or 10. The polypeptide can comprise the sequence set forth in SEQ ID NO:3, 5, 7, 9, or 11. The polypeptide can comprise the sequence set forth in SEQ ID NO:1. The polypeptide can comprise the sequence set forth in SEQ ID NO:43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, or 59 with no more than five additions, subtractions, or substitutions. The polypeptide can be from 17 to 45 amino acid residues, from 17 to 40 amino acid residues, from 17 to 35 amino acid residues, from 20 to 50 amino acid residues, from 25 to 50 amino acid residues, from 20 to 45 amino acid residues, from 20 to 40 amino acid residues, from 20 to 35 amino acid residues, from 25 to 45 amino acid residues, from 25 to 40 amino acid residues, or from 25 to 35 amino acid residues, in length.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a structural schematic of a chimeric polypeptide containing an N-terminus and ring structure of a natriuretic peptide and a C-terminus of a segment of an angiotensin polypeptide in accordance with some embodiments. The amino acid segment of an angiotensin polypeptide shown in FIG. 1 (DRVYIHP; SEQ ID NO:1) can be referred to as angiotensin-(1-7) or Ang-(1-7). The N-terminus and ring structure can have the sequence of any appropriate natriuretic peptide including, without limitation, ANP, BNP, CNP, DNP, and URO. “A” refers to an amino acid sequence from the N-terminus of a natriuretic peptide, “B” refers to an amino acid sequence from the ring structure of a natriuretic peptide, and “C” refers to an amino acid sequence of Ang(1-7), which can form the C-terminus of a chimeric polypeptide.

FIG. 2 is a structural schematic of a chimeric polypeptide (SEQ ID NO:43) containing an N-terminus and ring structure of ANP and a C-terminal Ang-(1-7) in accordance with some embodiments. The amino acid sequence of the N-terminal segment of ANP shown in FIG. 2 (SLRRSS; SEQ ID NO:2) can be referred to as ANP_(N-term), while the amino acid sequence of the ring structure segment of ANP shown in FIG. 2 (CFGGRMDRIGAQ-SGLGC; SEQ ID NO:3) can be referred to as ANP_(ring).

FIG. 3 is a structural schematic of a chimeric polypeptide (SEQ ID NO:44) containing an N-terminus and ring structure of BNP and a C-terminal Ang-(1-7) in accordance with some embodiments. The amino acid sequence of the N-terminal segment of BNP shown in FIG. 3 (SPKMVQGSG; SEQ ID NO:4) can be referred to as BNP_(N-term), while the amino acid sequence of the ring structure segment of BNP shown in FIG. 3 (CFGRKM-DRISSSSGLGC; SEQ ID NO:5) can be referred to as BNP_(ring). The chimeric polypeptide having the amino acid sequence set forth in SEQ ID NO:44 can be referred to as BNP-Ang1-7.

FIG. 4 is a structural schematic of a chimeric polypeptide (SEQ ID NO:45) containing an N-terminus and ring structure of CNP and a C-terminal Ang-(1-7) in accordance with some embodiments. The amino acid sequence of the N-terminal segment of CNP shown in FIG. 4 (GLSKG; SEQ ID NO:6) can be referred to as CNP_(N-term), while the amino acid sequence of the ring structure segment of CNP shown in FIG. 4 (CFGLKLDRIG-SMSGLGC; SEQ ID NO:7) can be referred to as CNP_(ring). The chimeric polypeptide shown in FIG. 4 can be referred to as cAng or cANG

FIG. 5 is a structural schematic of a chimeric polypeptide (SEQ ID NO:46) containing an N-terminus and ring structure of DNP and a C-terminal Ang-(1-7) in accordance with some embodiments. The amino acid sequence of the N-terminal segment of DNP shown in FIG. 5 (EVKYDP; SEQ ID NO:8) can be referred to as DNP_(N-term), while the amino acid sequence of the ring structure segment of DNP shown in FIG. 5 (CFGHKIDRINHVS-NLGC; SEQ ID NO:9) can be referred to as DNP_(ring).

FIG. 6 is a structural schematic of a chimeric polypeptide (SEQ ID NO:47) containing an N-terminus and ring structure of URO and a C-terminal Ang-(1-7) in accordance with some embodiments. The amino acid sequence of the N-terminal segment of URO shown in FIG. 6 (TAPRSLRRSS; SEQ ID NO:10) can be referred to as URO_(N-term), while the amino acid sequence of the ring structure segment of URO shown in FIG. 6 (CFGG-RMDRIGAQSGLGC; SEQ ID NO:11) can be referred to as URO_(ring).

FIG. 7 is a structural schematic of a chimeric polypeptide (SEQ ID NO:48) containing an N-terminus of BNP (BNP_(N-term)), a ring structure of ANP (ANP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 8 is a structural schematic of a chimeric polypeptide (SEQ ID NO:49) containing an N-terminus of CNP (CNP_(N-term)), a ring structure of ANP (ANP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 9 is a structural schematic of a chimeric polypeptide (SEQ ID NO:50) containing an N-terminus of DNP (DNP_(N-term)), N a ring structure of ANP (ANP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 10 is a structural schematic of a chimeric polypeptide (SEQ ID NO:51) containing an N-terminus of URO (URO_(N-term)), a ring structure of ANP (ANP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 11 is a structural schematic of a chimeric polypeptide (SEQ ID NO:52) containing an N-terminus of ANP (ANP_(N-term)), a ring structure of BNP (BNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 12 is a structural schematic of a chimeric polypeptide (SEQ ID NO:53) containing an N-terminus of CNP (CNP_(N-term)), a ring structure of BNP (BNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 13 is a structural schematic of a chimeric polypeptide (SEQ ID NO:54) containing an N-terminus of DNP (DNP_(N-term)), a ring structure of BNP (BNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 14 is a structural schematic of a chimeric polypeptide (SEQ ID NO:55) containing an N-terminus of URO (URO_(N-term)), a ring structure of BNP (BNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 15 is a structural schematic of a chimeric polypeptide (SEQ ID NO:56) containing an N-terminus of ANP (ANP_(N-term)), a ring structure of CNP (CNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 16 is a structural schematic of a chimeric polypeptide (SEQ ID NO:57) containing an N-terminus of BNP (BNP_(N-term)), a ring structure of CNP (CNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 17 is a structural schematic of a chimeric polypeptide (SEQ ID NO:58) containing an N-terminus of DNP (DNP_(N-term)), a ring structure of CNP (CNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 18 is a structural schematic of a chimeric polypeptide (SEQ ID NO:59) containing an N-terminus of URO (URO_(N-term)), a ring structure of CNP (CNP_(ring)), and a C-terminal Ang-(1-7) in accordance with some embodiments.

FIG. 19 is a structural schematic of a chimeric polypeptide (SEQ ID NO:60) containing an N-terminal Ang-(1-7) and a ring structure (ANP_(ring)) and C-terminus of ANP in accordance with some embodiments. The amino acid sequence of the C-terminal segment of ANP shown in FIG. 19 (NSFRY; SEQ ID NO:12) can be referred to as ANP_(C-term).

FIG. 20 is a structural schematic of a chimeric polypeptide (SEQ ID NO:61) containing an N-terminal Ang-(1-7) and a ring structure (BNP_(ring)) and C-terminus of BNP in accordance with some embodiments. The amino acid sequence of the C-terminal segment of BNP shown in FIG. 20 (KVLRRH; SEQ ID NO:13) can be referred to as BNP_(C-term). The chimeric polypeptide having the amino acid sequence set forth in SEQ ID NO:61 can be referred to as Ang1-7BNP.

FIG. 21 is a graph plotting the level of cGMP (pmol/mL) produced by human cardiac fibroblasts when exposed to ANP (10⁻⁶M), BNP (10⁻⁶M), CNP (10⁻⁶M), or cANG (10⁻⁶, 10⁻⁸, or 10⁻¹⁰ M).

FIG. 22 is a graph plotting the level of cGMP (pmol/mL) produced by human cardiac fibroblasts when exposed to ANP (10⁻⁶M), BNP (10⁻⁶M), CNP (10⁻⁶M), or cANG (10⁻⁶M) either alone or in the presence of A-71915 (1 μM; an NPR-A blocker (see, e.g., Kumar et al., Hypertension, 29(1 Pt 2):414-21 (1997))) or an NPR-B antibody (1:100 dilution).

FIG. 23 is a structural schematic of a chimeric polypeptide (SEQ ID NO:27) containing an N-terminal Ang-(1-7) and the C-terminus of ANP (ANP_(C-term)) without a ring structure in accordance with some embodiments. This polypeptide can be referred to as Ang-(1-7)-ANP-CT.

FIG. 24 is a structural schematic of a chimeric polypeptide (SEQ ID NO:28) containing an N-terminal Ang-(1-7) and the C-terminus of BNP (BNP_(C-term)) without a ring structure in accordance with some embodiments. This polypeptide can be referred to as Ang-(1-7)-BNP-CT.

FIG. 25 is a structural schematic of a chimeric polypeptide (SEQ ID NO:29) containing an N-terminal Ang-(1-7) and the C-terminus of DNP (DNP_(C-term)) without a ring structure in accordance with some embodiments. This polypeptide can be referred to as Ang-(1-7)-DNP-CT. The amino acid sequence of the C-terminal segment of DNP shown in FIG. 25 (PSLRDPRPNAPSTSA; SEQ ID NO:30) can be referred to as DNP_(C-term).

FIG. 26 is a structural schematic of a chimeric polypeptide (SEQ ID NO:31) containing the C-terminus of ANP (ANP_(C-term)) as an N-terminal segment followed by a C-terminal Ang-(1-7) without a ring structure in accordance with some embodiments. This polypeptide can be referred to as ANP-CT-Ang-(1-7).

FIG. 27 is a structural schematic of a chimeric polypeptide (SEQ ID NO:32) containing the C-terminus of BNP (BNP_(C-term)) as an N-terminal segment followed by a C-terminal Ang-(1-7) without a ring structure in accordance with some embodiments. This polypeptide can be referred to as BNP-CT-Ang-(1-7).

FIG. 28 is a structural schematic of a chimeric polypeptide (SEQ ID NO:33) containing the C-terminus of DNP (DNP_(C-term)) as an N-terminal segment followed by a C-terminal Ang-(1-7) without a ring structure in accordance with some embodiments. This polypeptide can be referred to as DNP-CT-Ang-(1-7).

FIG. 29 is a structural schematic of a chimeric polypeptide (SEQ ID NO:34) containing an N-terminal Ang-(1-7) and a ring structure (CNP_(ring)) with no C-terminal tail in accordance with some embodiments. This polypeptide can be referred to as Ang-(1-7)-CNPR1.

FIG. 30 is a structural schematic of a chimeric polypeptide (SEQ ID NO:35) containing a reverse ring structure of CNP and an C-terminal Ang-(1-7) and with no N-terminal tail in accordance with some embodiments. This polypeptide can be referred to as Ang-(1-7)-CNPR2. The amino acid sequence of the reverse ring structure segment of CNP shown in FIG. 30 (CGLGSMSGIRDLKLGFC; SEQ ID NO:36) can be referred to as reverse-CNP_(ring).

FIG. 31 is a structural schematic of a chimeric polypeptide (SEQ ID NO:37) containing an N-terminal Ang-(1-7) and a reverse ring structure (reverse-CNP_(ring)) with no C-terminal tail in accordance with some embodiments. This polypeptide can be referred to as Ang-(1-7)-CNPR3.

FIG. 32 is a structural schematic of a chimeric polypeptide (SEQ ID NO:38) containing a ring structure (CNP_(ring)) and an C-terminal Ang-(1-7) and with no N-terminal tail in accordance with some embodiments. This polypeptide can be referred to as Ang-(1-7)-CNPR4.

FIG. 33 contains graphs plotting cGMP levels resulting from treatment of HEK 293 cells with the indicated amount (10⁻⁶, 10⁻⁸, or 10⁻¹⁰ M) of BNP (BNP1-32; FIG. 33A), Ang1-7BNP (FIG. 33B), or BNP-Ang1-7 (FIG. 33C). The HEK 293 cells were stably transfected to express NPR-A (i.e., GC-A).

FIG. 34 contains graphs plotting cGMP levels resulting from treatment of HEK 293 cells with the indicated amount (10⁻⁶, 10⁻⁸, or 10⁻¹⁰ M) of BNP (BNP1-32; FIG. 34A), Ang1-7BNP (FIG. 34B), or BNP-Ang1-7 (FIG. 34C). The HEK 293 cells were stably transfected to express NPR-B (i.e., GC-B).

FIG. 35 contains graphs plotting cGMP levels resulting from treatment of HEK 293 cells with the indicated amount (10⁻⁶, 10⁻⁸, or 10⁻¹⁰ M) of Ang1-7. The HEK 293 cells were stably transfected to express NPR-A (i.e., GC-A) (left graph) or NPR-B (i.e., GC-B) (right graph).

DETAILED DESCRIPTION

This document provides methods and materials related to natriuretic polypeptides and the use of natriuretic polypeptides to treat cardiovascular and/or renal conditions. For example, this document provides chimeric polypeptides having at least one amino acid segment (e.g., N-terminus tail, ring structure, reverse ring structure, C-terminus tail, or a combination thereof) of a natriuretic peptide (e.g., ANP, BNP, CNP, URO, or DNP) and an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7), Ang-(1-8), or Ang-(1-9)). In some cases, a chimeric polypeptide provided herein can be used to increase natriuretic activity in a subject in need thereof. In some cases, a chimeric polypeptide provided herein can be used to increase plasma cGMP levels, urinary cGMP excretion, net renal cGMP generation, urine flow, urinary sodium excretion, urinary potassium excretion, hematocrit, plasma BNP immunoreactivity, renal blood flow, and/or plasma ANP immunoreactivity. In some cases, a chimeric polypeptide provided herein can be used to decrease renal vascular resistance, proximal and distal fractional reabsorption of sodium, mean arterial pressure, pulmonary capillary wedge pressure, right atrial pressure, pulmonary arterial pressure, plasma renin activity, plasma angiotensin II levels, plasma aldosterone levels, renal perfusion pressure, and/or systemic vascular resistance. In some cases, a chimeric polypeptide provided herein can be used to treat, inhibit, and/or prevent cardiac remodeling and ischemia-reperfusion injury, particularly after acute myocardial infarction (AMI) and/or acute heart failure (AHF). For example, a chimeric polypeptide provided herein can be used to increase plasma cGMP, which may be desirable for applications in attenuating myocardial ischemia-reperfusion injury (Padilla et al., Cardiovasc. Res., 51:592-600 (2001)).

As described herein, a chimeric polypeptide can be designed to include at least one amino acid segment (e.g., N-terminus tail, ring structure, reverse ring structure, C-terminus tail, or a combination thereof) of a natriuretic peptide and an amino acid segment of an angiotensin polypeptide. Examples of natriuretic peptides or “NPs” include, without limitation, ANP, BNP, CNP, URO, and DNP. A chimeric polypeptide provided herein can include any appropriate amino acid segment of an angiotensin polypeptide (e.g., human angiotensin polypeptide). For example, a chimeric polypeptide provided herein can include the sequence set forth in SEQ ID NO:1. In some cases, a chimeric polypeptide provided herein can include a full length angiotensin polypeptide (e.g., a full length human angiotensin polypeptide). For example, a chimeric polypeptide provided herein can include the following sequence: DRVYIHPFHL (SEQ ID NO:14).

A chimeric polypeptide provided herein can include a ring structure of a natriuretic peptide. Examples of ring structures include, without limitation, ANP_(ring), BNP_(ring), CNP_(ring), DNP_(ring), and URO_(ring). In some cases, an ANP_(ring), BNP_(ring), CNP_(ring), DNP_(ring), or URO_(ring) having one or more (e.g., one, two, three, four, five, six, or more) amino acid additions, subtractions, or substitutions can be used. For example, an ANP_(ring) or BNP_(ring) having two amino acid substitutions can be used as a ring structure of a chimeric polypeptide provided herein.

In some cases, a chimeric polypeptide provided herein includes a reverse ring structure of a natriuretic peptide. Examples of reverse ring structures include, without limitation, reverse-ANP_(ring) (CGLGSQAGIRDMRGGFC; SEQ ID NO:39), reverse-BNP_(ring) (CGLGSSSSIRDMKRGFC; SEQ ID NO:40), reverse-CNP_(ring), reverse-DNP_(ring) (CGLNSVHNIRDIKHGFC; SEQ ID NO:41), and reverse-URO_(ring) (CGLGSQAGIRDMRGGFC; SEQ ID NO:42). In some cases, a reverse-ANP_(ring), reverse-BNP_(ring), reverse-CNP_(ring), reverse-DNP_(ring), or reverse-URO_(ring) having one or more (e.g., one, two, three, four, five, six, or more) amino acid additions, subtractions, or substitutions can be used. For example, a reverse-ANP_(ring) or reverse-BNP_(ring) having two amino acid substitutions can be used as a ring structure of a chimeric polypeptide provided herein.

In some cases, a chimeric polypeptide provided herein can include any appropriate amino acid segment of an angiotensin polypeptide either as an N-terminal portion or as a C-terminal portion with respect to a ring structure or reverse ring structure for those polypeptides containing such a ring structure or reverse ring structure. For example, a chimeric polypeptide provided herein can include an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7)) followed by a ring structure and optionally a C-terminus of a natriuretic peptide (e.g., ANP_(C-term), BNP_(C-term), or DNP_(C-term)). In some cases, an optional N-terminus of a natriuretic peptide (e.g., ANP_(N-term) or BNP_(N-term)) can be followed by a ring structure of a natriuretic peptide and an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7)).

In some cases, a chimeric polypeptide provided herein can include any appropriate amino acid segment of an angiotensin polypeptide either as an N-terminal portion or as a C-terminal portion attached to an N-terminus (e.g., ANP_(N-term), BNP_(N-term), CNP_(N-term), DNP_(N-term), or URO_(N-term)) or C-terminus of a natriuretic peptide (e.g., ANP_(C-term), BNP_(C-term), or DNP_(C-term)) without a ring or reverse ring structure. For example, a chimeric polypeptide provided herein can include an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7)) followed by a C-terminus of a natriuretic peptide (e.g., ANP_(C-term) or BNP_(C-term)) without a ring or reverse ring structure. In some cases, a C-terminus of a natriuretic peptide (e.g., ANP_(C-term) or BNP_(C-term)) can be followed by an amino acid segment of an angiotensin polypeptide (e.g., Ang-(1-7)) without a ring or reverse ring structure.

With reference to FIG. 1, a chimeric polypeptide provided herein can include an N-terminus and ring structure of a natriuretic peptide and a C-terminal Ang-(1-7). In some cases, the N-terminus and ring structure can be of the same natriuretic peptide (see, e.g., FIGS. 2-6) or of different natriuretic peptides (see, e.g., FIG. 7-18). For example, a chimeric polypeptide provided herein can have BNP_(N-term) followed by BNP_(ring) followed by Ang-(1-7) as shown in FIG. 3 or can have ANP_(N-term) followed by BNP_(ring) followed by Ang-(1-7) as shown in FIG. 11. In some cases, a chimeric polypeptide provided herein can include an N-terminal Ang-(1-7) followed by a ring structure and C-terminus of a natriuretic peptide as shown in FIGS. 19 and 20.

In some cases, an N-terminus, ring structure, reverse ring structure, and/or C-terminus of an NP included in a chimeric polypeptide provided herein can include a variant (e.g., a substitution, addition, or deletion) at one or more positions (e.g., one, two, three, four, five, six, seven, eight, nine, or ten positions). Such variant NP sequences, e.g., those having one or more amino acid substitutions relative to a native NP amino acid sequence, can be prepared and modified as described herein. Amino acid substitutions can be made, in some cases, by selecting substitutions that do not differ significantly in their effect on maintaining (a) the structure of the peptide backbone in the area of the substitution, (b) the charge or hydrophobicity of the molecule at the target site, or (c) the bulk of the side chain. For example, naturally occurring residues can be divided into groups based on side-chain properties: (1) hydrophobic amino acids (norleucine, methionine, alanine, valine, leucine, and isoleucine); (2) neutral hydrophilic amino acids (cysteine, serine, and threonine); (3) acidic amino acids (aspartic acid and glutamic acid); (4) basic amino acids (asparagine, glutamine, histidine, lysine, and arginine); (5) amino acids that influence chain orientation (glycine and proline); and (6) aromatic amino acids (tryptophan, tyrosine, and phenylalanine). Substitutions made within these groups can be considered conservative substitutions. Non-limiting examples of useful substitutions include, without limitation, substitution of valine for alanine, lysine for arginine, glutamine for asparagine, glutamic acid for aspartic acid, serine for cysteine, asparagine for glutamine, aspartic acid for glutamic acid, proline for glycine, arginine for histidine, leucine for isoleucine, isoleucine for leucine, arginine for lysine, leucine for methionine, leucine for phenyalanine, glycine for proline, threonine for serine, serine for threonine, tyrosine for tryptophan, phenylalanine for tyrosine, and/or leucine for valine.

Examples of variant N-terminal portions of NP sequences that can be used to make a chimeric polypeptide provided herein include, without limitation, SAPRSLRRSS (SEQ ID NO:15), TVPRSLRRSS (SEQ ID NO:16), TAGRSLRRSS (SEQ ID NO:17), TAPKSLRRSS (SEQ ID NO:18), TLRRSS (SEQ ID NO:19), SIRRSS (SEQ ID NO:20), SLKRSS (SEQ ID NO:21), and SLRKSS (SEQ ID NO:22). Examples of variant C-terminal portions of NP sequences that can be used to make a chimeric polypeptide provided herein include, without limitation, KVLRRR (SEQ ID NO:23), KVLRKH (SEQ ID NO:24), KVLKRH (SEQ ID NO:25), and KVIRRH (SEQ ID NO:26).

Further examples of conservative substitutions that can be made at any position within an NP amino acid sequence used to make a chimeric polypeptide provided herein include, without limitation, those set forth in Table 1.

TABLE 1 Examples of conservative amino acid substitutions. Original Residue Exemplary substitutions Ala Val, Leu, Ile Arg Lys, Gln, Asn Asn Gln, His, Lys, Arg Asp Glu Cys Ser Gln Asn Glu Asp Gly Pro His Asn, Gln, Lys, Arg Ile Leu, Val, Met, Ala, Phe, Norleucine Leu Norleucine, Ile, Val, Met, Ala, Phe Lys Arg, Gln, Asn Met Leu, Phe, Ile Phe Leu, Val, Ile, Ala Pro Gly Ser Thr Thr Ser Trp Tyr Tyr Trp, Phe, Thr, Ser Val Ile, Leu, Met, Phe, Ala, Norleucine

In some cases, an NP amino acid sequence used to make a chimeric polypeptide provided herein can include one or more non-conservative substitutions. Non-conservative substitutions typically entail exchanging a member of one of the classes described above for a member of another class. Such production can be desirable to provide large quantities or alternative embodiments of such compounds. Whether an amino acid change results in a functional polypeptide can readily be determined by assaying the specific activity of the peptide variant.

A chimeric polypeptide provided herein can have any appropriate sequence. For example, a polypeptide can include the sequences set forth in SEQ ID NOs:2, 3, and 1. In some cases, a chimeric polypeptide provided herein can contain (a) an amino acid sequence that aligns to the sequence set forth in SEQ ID NO:1 with three or less (e.g., two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations thereof and (b) an amino acid sequence that aligns to the sequence of ANP_(ring), BNP_(ring), CNP_(ring), DNP_(ring), or URO_(ring) with five or less (e.g., four or less, three or less, two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations thereof. In some cases, a chimeric polypeptide provided herein can contain (a) an amino acid sequence that aligns to the sequence set forth in SEQ ID NO:1 with three or less (e.g., two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations thereof followed by (b) an amino acid sequence that aligns to the sequence of ANP_(ring), BNP_(ring), CNP_(ring), DNP_(ring), or URO_(ring) with five or less (e.g., four or less, three or less, two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations thereof followed by (c) an amino acid sequence that aligns to the sequence of ANP_(C-term), BNP_(C-term), or a DNP_(C-term) sequence with five or less (e.g., four or less, three or less, two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations thereof. In some cases, a chimeric polypeptide provided herein can contain (a) an amino acid sequence that aligns to the sequence of ANP_(N-term), BNP_(N-term), CNP_(N-term), DNP_(N-term), or URO_(N-term) with five or less (e.g., four or less, three or less, two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations thereof followed by (b) an amino acid sequence that aligns to the sequence of ANP_(ring), BNP_(ring), CNP_(ring), DNP_(ring), or URO_(ring) with five or less (e.g., four or less, three or less, two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations thereof followed by an amino acid sequence that aligns to the sequence set forth in SEQ ID NO:1 with three or less (e.g., two or less, one, or zero) amino acid additions, deletions, substitutions, or combinations.

A polypeptide provided herein can have any appropriate length. For example, a polypeptide provided herein can be between 20 and 55 (e.g., between 24 and 55, between 24 and 45, between 25 and 45, between 26 and 44, between 27 and 43, between 28 and 42, between 29 and 41, between 30 and 40, between 31 and 39, between 23 and 35, between 25 and 30, or between 30 and 35) amino acid residues in length. It will be appreciated that a polypeptide with a length of 20 or 55 amino acid residues is a polypeptide with a length between 20 and 55 amino acid residues.

Chimeric polypeptides provided herein as well as polypeptides containing a variant NP sequence with conservative and/or non-conservative substitutions (e.g., with respect to a natural ANP, BNP, CNP, DNP, or URO), fragments of ANP, BNP, CNP, DNP, or URO, or fragments of such variants can be assessed for biological activity using any suitable assay including, without limitation, those described herein. For example, the activity of a chimeric polypeptide having a variant NP amino acid sequence as described herein can be evaluated in vitro by measuring its effect on cGMP levels generated by cardiac fibroblasts (CFs) or by testing its ability to suppress proliferation of CFs. Such experiments can be performed, for example, in human CFs (ScienCell, San Diego, Calif.) as described elsewhere (Tsuruda et al., Circ. Res. 91:1127-1134 (2002)). Cells can be exposed to a polypeptide to be assessed (e.g., 10⁻¹¹ to 10⁻⁶ M), and samples can be assayed for cGMP using a competitive RIA cGMP kit (Perkin-Elmer, Boston, Mass.). For CF proliferation studies, cells can be treated with Cardiotrophin-1 to induce cell proliferation. A polypeptide to be assessed can be added to the Cardiotrophin-1-stimulated CFs to determine its effect on cell proliferation. Cell proliferation can be detected and measured using, for example, a colormetric bromodeoxyuridine (BrdU) cell proliferation ELISA (Roche, Indianapolis, Ind.).

In some cases, a chimeric polypeptide provided herein, a polypeptide containing a variant NP sequence with conservative and/or non-conservative substitutions (e.g., with respect to a natural ANP, BNP, CNP, DNP, or URO), a fragment of ANP, BNP, CNP, DNP, or URO, or a fragment of such variants can be assessed in vivo by, for example, testing its effects on factors such as pulmonary capillary wedge pressure, right atrial pressure, mean arterial pressure, urinary sodium excretion, urine flow, proximal and distal fractional sodium reabsorption, plasma renin activity, plasma cGMP levels, urinary cGMP excretion, net renal generation of cGMP, glomerular filtration rate, and left ventricular mass in animals. In some cases, such parameters can be evaluated after induced myocardial infarction (e.g., myocardial infarction induced by coronary artery ligation).

In some embodiments, a chimeric polypeptide provided herein can be cyclic due to disulfide bonds between cysteine residues (see, e.g., the structures depicted in FIGS. 1-20). In some embodiments, a sulfhydryl group on a cysteine residue can be replaced with an alternative group (e.g., —CH₂CH₂—). To replace a sulfhydryl group with a —CH₂— group, for example, a cysteine residue can be replaced by alpha-aminobutyric acid. Such cyclic analog polypeptides can be generated, for example, as described elsewhere (Lebl and Hruby, Tetrahedron Lett., 25:2067 (1984) and U.S. Pat. No. 4,161,521).

In some cases, ester or amide bridges can be formed by reacting the OH of serine or threonine with the carboxyl group of aspartic acid or glutamic acid to yield a bridge having the structure —CH₂CO₂CH₂—. In some cases, an amide can be obtained by reacting the side chain of lysine with aspartic acid or glutamic acid to yield a bridge having the structure —CH₂C(O)NH(CH)₄—. Methods for synthesis of these bridges are described elsewhere (see, e.g., Schiller et al., Biochem. Biophy. Res. Comm., 127:558 (1985), and Schiller et al. Int. J. Peptide Protein Res., 25:171 (1985)). Other bridge-forming amino acid residues and reactions are provided in, for example, U.S. Pat. No. 4,935,492. In some cases, peptide analogs that include non-peptidyl bonds can be used to link amino acid residues of a chimeric polypeptide provided herein as described elsewhere (See, e.g., Spatola et al., Life Sci., 38:1243 (1986); Spatola, Vega Data, 1(3) (1983); Morley, Trends Pharm. Sci., 463-468 (1980); Hudson et al., Int. J. Pept. Prot. Res., 14:177 (1979); Spatola, in Chemistry and Biochemistry of Amino Acid Peptides and Proteins, B. Weinstein, ed., Marcel Dekker, New York, p. 267 (1983); Hann, J. Chem. Soc. Perkin Trans., 1:307 (1982); Almquist et al., J. Med. Chem. 23:1392 (1980); Jennings-White et al., Tetrahedron Lett., 23:2533 (1982); European Patent Application EP 45665; Holladay et al., Tetrahedron Lett., 24:4401 (1983); and Hruby, Life Sci., 31:189 (1982).

In some cases, a chimeric polypeptide provided herein can have an amino acid sequence with at least 85% (e.g., 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to a reference sequence (e.g., SEQ ID NO:1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, or 61). Percent sequence identity is calculated by determining the number of matched positions in aligned amino acid sequences (target amino acid sequence aligned to an identified amino acid sequence), dividing the number of matched positions by the number of amino acids of the identified amino acid sequence (e.g., SEQ ID NO:3), and multiplying by 100. A matched position refers to a position in which identical amino acids occur at the same position in aligned amino acid sequences. Percent sequence identity also can be determined for any nucleic acid sequence.

Percent sequence identity is determined by comparing a target amino acid sequence to the identified amino acid sequence (e.g., SEQ ID NO:3) using the BLAST 2 Sequences (Bl2seq) program from the stand-alone version of BLASTZ containing BLASTN version 2.0.14 and BLASTP version 2.0.14. This stand-alone version of BLASTZ can be obtained on the World Wide Web from Fish & Richardson's web site (fr.com/blast) or the U.S. government's National Center for Biotechnology Information web site (ncbi.nlm.nih.gov). Instructions explaining how to use the Bl2seq program can be found in the readme file accompanying BLASTZ.

Bl2seq performs a comparison between two sequences using either the BLASTN or BLASTP algorithm. BLASTN is used to compare nucleic acid sequences, while BLASTP is used to compare amino acid sequences. To compare two nucleic acid sequences, the options are set as follows: -i is set to a file containing the first nucleic acid sequence to be compared (e.g., C:\seq1.txt); -j is set to a file containing the second nucleic acid sequence to be compared (e.g., C:\seq2.txt); -p is set to blastn; -o is set to any desired file name (e.g., C:\output.txt); -q is set to -1; -r is set to 2; and all other options are left at their default setting. The following command will generate an output file containing a comparison between two sequences: C:\Bl2seq c:\seq1.txt -j c:\seq2.txt -p blastn -o c:\output.txt -q -1 -r 2. If the target sequence shares homology with any portion of the identified sequence, then the designated output file will present those regions of homology as aligned sequences. If the target sequence does not share homology with any portion of the identified sequence, then the designated output file will not present aligned sequences.

For example, if (1) a target sequence is compared to the sequence set forth in SEQ ID NO:3 and (2) the Bl2seq program presents the target sequence aligned with a region of the sequence set forth in SEQ ID NO:3 with the number of matches being 15, then the amino acid target sequence has a percent identity to SEQ ID NO:3 that is 88.2 (i.e., 15÷17×100=88.2). It is noted that the percent identity value is rounded to the nearest tenth. For example, 78.11, 78.12, 78.13, and 78.14 are rounded down to 78.1, while 78.15, 78.16, 78.17, 78.18, and 78.19 are rounded up to 78.2. It also is noted that the length value will always be an integer.

A chimeric polypeptide provided herein can be produced using any suitable method, including solid phase synthesis, and can be generated using manual techniques or automated techniques (e.g., using an Applied BioSystems (Foster City, Calif.) Peptide Synthesizer or a Biosearch Inc. (San Rafael, Calif.) automatic peptide synthesizer). Disulfide bonds between cysteine residues can be introduced by mild oxidation of the linear polypeptides using KCN as described elsewhere (U.S. Pat. No. 4,757,048). In some cases, a chimeric polypeptide provided herein can be produced recombinantly, as described herein.

In some cases, a chimeric polypeptide provided herein can be a substantially pure polypeptide. As used herein, the term “substantially pure” with reference to a polypeptide means that the polypeptide is substantially free of other polypeptides, lipids, carbohydrates, and nucleic acid. In some cases, a substantially pure polypeptide can be a polypeptide that is at least 60 percent pure or is any chemically synthesized polypeptide. A substantially pure polypeptide can be at least about 60, 65, 70, 75, 80, 85, 90, 95, or 99 percent pure. Typically, a substantially pure polypeptide will yield a single major band on a non-reducing polyacrylamide gel.

Salts of carboxyl groups of a chimeric polypeptide provided herein can be prepared by contacting the polypeptide with one or more equivalents of a desired base such as, for example, a metallic hydroxide base (e.g., sodium hydroxide), a metal carbonate or bicarbonate base (e.g., sodium carbonate or sodium bicarbonate), or an amine base (e.g., triethylamine, triethanolamine, and the like). Acid addition salts of a chimeric polypeptide provided herein can be prepared by contacting the polypeptide with one or more equivalents of an inorganic or organic acid (e.g., hydrochloric acid).

Esters of carboxyl groups of a chimeric polypeptide provided herein can be prepared using any suitable means for converting a carboxylic acid or precursor to an ester. For example, one method for preparing esters of a chimeric polypeptide provided herein, when using the Merrifield synthesis technique, is to cleave the completed polypeptide from the resin in the presence of the desired alcohol under either basic or acidic conditions, depending upon the resin. The C-terminal end of the polypeptide then can be directly esterified when freed from the resin, without isolation of the free acid.

Amides of a chimeric polypeptide provided herein can be prepared using techniques for converting a carboxylic acid group or precursor to an amide. One method for amide formation at the C-terminal carboxyl group includes cleaving the polypeptide from a solid support with an appropriate amine, or cleaving in the presence of an alcohol, yielding an ester, followed by aminolysis with the desired amine.

N-acyl derivatives of an amino group of a chimeric polypeptide provided herein can be prepared by utilizing an N-acyl protected amino acid for the final condensation, or by acylating a protected or unprotected polypeptide. O-acyl derivatives can be prepared for example, by acylation of a free hydroxy peptide or peptide resin. Either acylation may be carried out using standard acylating reagent such as acyl halides, anhydrides, acyl imidazoles, and the like. Both N- and O-acylation may be carried out together, if desired.

In some cases, a chimeric polypeptide provided herein can be modified by linkage to a polymer such as polyethylene glycol (PEG), or by fusion to another polypeptide such as albumin, for example. For example, one or more PEG moieties can be conjugated to a chimeric polypeptide provided herein via lysine residues. Linkage to PEG or another suitable polymer, or fusion to albumin or another suitable polypeptide can result in a modified chimeric polypeptide having an increased half life as compared to an unmodified chimeric polypeptide. Without being bound by a particular mechanism, an increased serum half life can result from reduced proteolytic degradation, immune recognition, or cell scavanging of the modified chimeric polypeptide. Any appropriate method can be used to modify a chimeric polypeptide by linkage to PEG (also referred to as “PEGylation”) or other polymers including, without limitation, those described elsewhere (U.S. Pat. No. 6,884,780; Cataliotti et al., Trends Cardiovasc. Med., 17: 10-14 (2007); Veronese and Mero, BioDrugs, 22:315-329 (2008); Miller et al., Bioconjugate Chem., 17:267-274 (2006); and Veronese and Pasut, Drug Discov. Today, 10:1451-1458 (2005). Examples of methods for modifying a chimeric polypeptide by fusion to albumin include, without limitation, those described elsewhere (U.S. Patent Publication No. 20040086976, and Wang et al., Pharm. Res., 21:2105-2111 (2004)).

The term “cardiac remodeling” refers to effects on the heart that can occur with myocardial infarction, acute heart failure, or other conditions. These include, for example, heart dilation, myocyte hypertrophy, and cardiofibrosis (i.e., proliferation of interstitial fibroblasts). The chimeric polypeptides provided herein can be used to inhibit or prevent cardiac remodeling that occurs with myocardial infarction or acute heart failure. In some cases, parameters indicative of reduced cardiac remodeling can include one or more of the following: cardiac unloading (i.e., reduced pressure in the heart), increased glomerular filtration rate (GFR), decreased plasma renin activity (PRA), decreased levels of angiotensin II, decreased proliferation of cardiac fibroblasts, decreased left ventricular (LV) hypertrophy, decreased LV mass (indicative of reduced fibrosis and hypertrophy), decreased pulmonary capillary wedge pressure (PCWP; an indirect measure of left atrial pressure), decreased right atrial pressure, decreased mean arterial pressure, decreased levels of aldosterone (indicative of an anti-fibrotic effect), decreased ventricular fibrosis, increased ejection fraction, and decreased LV end systolic diameter. To determine whether a chimeric polypeptide provided herein is capable of inhibiting or reducing cardiac remodeling, one or more of these parameters can be evaluated (e.g., before and after treatment with the chimeric polypeptide), using methods known in the art and/or described herein, for example. The use of human amino acid sequences to construct a chimeric polypeptide provided herein can minimize the risk of immunogenicity that may be observed with protein therapeutics, as compared to the use of amino acid sequences from other species (Haller et al., Clin. Pharmacol. Ther, 84:624-7 (2008); and Leader et al., Nat. Rev. Drug Discov., 7:21-39 (2008)).

Conditions such as acute myocardial infarction (AMI) or acute heart failure (AHF) can lead to kidney damage as well as heart damage. In some cases, the chimeric polypeptides provided herein can protect the kidneys from damage after AMI and AHF. Parameters that are indicative of favorable renal actions include, for example, decreased proximal fractional reabsorption of sodium (PFRNa), decreased distal fractional reabsorption of sodium (DFRNa), increased urinary sodium excretion (UNaV), and increased urine flow (UV). Any one or more of these parameters can be assessed (e.g., before and after administration of a chimeric polypeptide) to determine whether the chimeric polypeptide has kidney protecting effects. Methods for assessing these parameters are known in the art, and also are described herein.

In some cases, a chimeric polypeptide provided herein can inhibit or reduce cardiac remodeling such as occurs after AMI or AHF, for example. A chimeric polypeptide that can inhibit cardiac remodeling is one that can alter one or more parameters indicative of inhibited or reduced cardiac remodeling by at least 10%. To determine whether a particular chimeric polypeptide has such properties, one can carry out assays that are well known to the art, including those described herein. A chimeric polypeptide that includes a variant NP sequence can have at least about 10% (e.g., at least about 10%, 15%, 20%, 25%, 33%, 40%, 50%, 60%, 67%, 75%, 80%, 85%, 90%, 95%, 100%, or more than 100%) of the biological activity of the corresponding wild type NP sequence.

Nucleic Acids, Vectors, and Host Cells

This document also provides nucleic acids encoding a chimeric polypeptide provided herein, as well as expression vectors containing the nucleic acids, and host cells containing the nucleic acids and/or expression vectors. As used herein, the term “nucleic acid” refers to both RNA and DNA, including cDNA, genomic DNA, and synthetic (e.g., chemically synthesized) DNA. A nucleic acid molecule can be double-stranded or single-stranded (i.e., a sense or an antisense single strand). Nucleic acids include, for example, cDNAs encoding the chimeric polypeptides provided herein.

An “isolated nucleic acid” is a nucleic acid that is separated from other nucleic acid molecules that are present in a vertebrate genome, including nucleic acids that normally flank one or both sides of the nucleic acid in a vertebrate genome. The term “isolated” as used herein with respect to nucleic acids also includes any non-naturally-occurring nucleic acid sequence, since such non-naturally-occurring sequences are not found in nature and do not have immediately contiguous sequences in a naturally-occurring genome.

An isolated nucleic acid can be, for example, a DNA molecule, provided one of the nucleic acid sequences normally found immediately flanking that DNA molecule in a naturally-occurring genome is removed or absent. Thus, an isolated nucleic acid includes, without limitation, a DNA molecule that exists as a separate molecule (e.g., a chemically synthesized nucleic acid, or a cDNA or genomic DNA fragment produced by PCR or restriction endonuclease treatment) independent of other sequences as well as DNA that is incorporated into a vector, an autonomously replicating plasmid, a virus (e.g., a retrovirus, lentivirus, adenovirus, or herpes virus), or into the genomic DNA of a prokaryote or eukaryote. In addition, an isolated nucleic acid can include an engineered nucleic acid such as a DNA molecule that is part of a hybrid or fusion nucleic acid. A nucleic acid existing among hundreds to millions of other nucleic acids within, for example, cDNA libraries or genomic libraries, or gel slices containing a genomic DNA restriction digest, is not considered an isolated nucleic acid.

Isolated nucleic acid molecules can be produced using standard techniques, including, without limitation, common molecular cloning and chemical nucleic acid synthesis techniques. For example, polymerase chain reaction (PCR) techniques can be used to obtain an isolated nucleic acid containing a nucleotide sequence that encodes an angiotensin polypeptide or an NP. PCR refers to a procedure or technique in which target nucleic acids are enzymatically amplified. Sequence information from the ends of the region of interest or beyond typically is employed to design oligonucleotide primers that are identical in sequence to opposite strands of the template to be amplified. PCR can be used to amplify specific sequences from DNA as well as RNA, including sequences from total genomic DNA or total cellular RNA. Primers typically are 14 to 40 nucleotides in length, but can range from 10 nucleotides to hundreds of nucleotides in length. General PCR techniques are described, for example in PCR Primer: A Laboratory Manual, ed. by Dieffenbach and Dveksler, Cold Spring Harbor Laboratory Press, 1995. When using RNA as a source of template, reverse transcriptase can be used to synthesize complementary DNA (cDNA) strands. Ligase chain reaction, strand displacement amplification, self-sustained sequence replication, or nucleic acid sequence-based amplification also can be used to obtain isolated nucleic acids. See, for example, Lewis (1992) Genetic Engineering News 12:1; Guatelli et al. (1990) Proc. Natl. Acad. Sci. USA 87:1874-1878; and Weiss (1991) Science 254:1292.

Isolated nucleic acids also can be chemically synthesized, either as a single nucleic acid molecule (e.g., using automated DNA synthesis in the 3′ to 5′ direction using phosphoramidite technology) or as a series of oligonucleotides. For example, one or more pairs of long oligonucleotides (e.g., >100 nucleotides) can be synthesized that contain the desired sequence, with each pair containing a short segment of complementarity (e.g., about 15 nucleotides) such that a duplex is formed when the oligonucleotide pair is annealed. DNA polymerase is used to extend the oligonucleotides, resulting in a single, double-stranded nucleic acid molecule per oligonucleotide pair, which then can be ligated into a vector.

Isolated nucleic acids (e.g., nucleic acids encoding variant NPs) also can be obtained by mutagenesis. For example, a reference sequence can be mutated using standard techniques including oligonucleotide-directed mutagenesis and site-directed mutagenesis through PCR. See, Short Protocols in Molecular Biology, Chapter 8, Green Publishing Associates and John Wiley & Sons, edited by Ausubel et al., 1992. Non-limiting examples of variant NPs art provided herein.

Sources of nucleotide sequences from which nucleic acid molecules encoding an NP, or the nucleic acid complement thereof, can be obtained include total or polyA⁺ RNA from any eukaryotic source, including reptilian (e.g., snake) or mammalian (e.g., human, rat, mouse, canine, bovine, equine, ovine, caprine, or feline) cellular source from which cDNAs can be derived by methods known in the art. Other sources of the nucleic acid molecules include genomic libraries derived from any eukaryotic cellular source, including mammalian sources.

Nucleic acid molecules encoding native NPs can be identified and isolated using standard methods, e.g., as described by Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, NY (1989). For example, reverse-transcriptase PCR (RT-PCR) can be used to isolate and clone NP cDNAs from isolated RNA that contains RNA sequences of interest (e.g., total RNA isolated from human tissue). Other approaches to identify, isolate, and clone NP cDNAs include, for example, screening cDNA libraries.

Vectors containing nucleic acids such as those described herein also are provided. A “vector” is a replicon, such as a plasmid, phage, or cosmid, into which another DNA segment may be inserted so as to bring about the replication of the inserted segment. An “expression vector” is a vector that includes one or more expression control sequences, and an “expression control sequence” is a DNA sequence that controls and regulates the transcription and/or translation of another DNA sequence.

In the expression vectors, a nucleic acid (e.g., a nucleic acid encoding a chimeric polypeptide provided herein) can be operably linked to one or more expression control sequences. As used herein, “operably linked” means incorporated into a genetic construct so that expression control sequences effectively control expression of a coding sequence of interest. Examples of expression control sequences include promoters, enhancers, and transcription terminating regions. A promoter is an expression control sequence composed of a region of a DNA molecule, typically within 100 to 500 nucleotides upstream of the point at which transcription starts (generally near the initiation site for RNA polymerase II). To bring a coding sequence under the control of a promoter, it is necessary to position the translation initiation site of the translational reading frame of the polypeptide between one and about fifty nucleotides downstream of the promoter. Enhancers provide expression specificity in terms of time, location, and level. Unlike promoters, enhancers can function when located at various distances from the transcription site. An enhancer also can be located downstream from the transcription initiation site. A coding sequence is “operably linked” and “under the control” of expression control sequences in a cell when RNA polymerase is able to transcribe the coding sequence into mRNA, which then can be translated into the protein encoded by the coding sequence.

Suitable expression vectors include, without limitation, plasmids and viral vectors derived from, for example, bacteriophage, baculoviruses, tobacco mosaic virus, herpes viruses, cytomegalovirus, retroviruses, vaccinia viruses, adenoviruses, and adeno-associated viruses. Numerous vectors and expression systems are commercially available from such corporations as Novagen (Madison, Wis.), Clontech (Palo Alto, Calif.), Stratagene (La Jolla, Calif.), and Invitrogen/Life Technologies (Carlsbad, Calif.).

An expression vector can include a tag sequence designed to facilitate subsequent manipulation of the expressed nucleic acid sequence (e.g., purification or localization). Tag sequences, such as green fluorescent protein (GFP), glutathione S-transferase (GST), polyhistidine, c-myc, hemagglutinin, or Flag™ tag (Kodak, New Haven, Conn.) sequences typically are expressed as a fusion with the encoded polypeptide. Such tags can be inserted anywhere within the polypeptide including at either the carboxyl or amino terminus.

This document also provides host cells containing a nucleic acid or vector provided herein. The term “host cell” is intended to include prokaryotic and eukaryotic cells into which a recombinant nucleic acid or vector (e.g., an expression vector) can be introduced. As used herein, “transformed” and “transfected” encompass the introduction of a nucleic acid molecule (e.g., a vector) into a cell by one of a number of techniques. Although not limited to a particular technique, a number of these techniques are well established within the art. Suitable methods for transforming and transfecting host cells can be found, for example, in Sambrook et al., Molecular Cloning: A Laboratory Manual (2^(nd) edition), Cold Spring Harbor Laboratory, New York (1989). For example, calcium phosphate precipitation, electroporation, heat shock, lipofection, microinjection, and viral-mediated nucleic acid transfer can be used introduce nucleic acid into cells. In addition, naked DNA can be delivered directly to cells in vivo as described elsewhere (U.S. Pat. Nos. 5,580,859 and 5,589,466).

Detecting Polypeptides

This document also provides methods and materials for detecting a chimeric polypeptide provided herein. Such methods and materials can be used to monitor chimeric polypeptide levels within a mammal receiving the chimeric polypeptide as a therapeutic. A chimeric polypeptide provided herein (e.g., a chimeric polypeptide as set forth in any one of FIGS. 2-20 and 23-32) can be detected, for example, immunologically using one or more antibodies. As used herein, the term “antibody” includes intact molecules as well as fragments thereof that are capable of binding to an epitopic determinant of a chimeric polypeptide provided herein. The term “epitope” refers to an antigenic determinant on an antigen to which the paratope of an antibody binds. Epitopic determinants usually consist of chemically active surface groupings of molecules such as amino acids or sugar side chains, and typically have specific three-dimensional structural characteristics, as well as specific charge characteristics. Epitopes generally have at least five contiguous amino acids (a continuous epitope), or alternatively can be a set of noncontiguous amino acids that define a particular structure (e.g., a conformational epitope). The term “antibody” includes polyclonal antibodies, monoclonal antibodies, humanized or chimeric antibodies, single chain Fv antibody fragments, Fab fragments, and F(ab)₂ fragments. Polyclonal antibodies are heterogeneous populations of antibody molecules that are contained in the sera of the immunized animals. Monoclonal antibodies are homogeneous populations of antibodies to a particular epitope of an antigen.

Antibody fragments that have specific binding affinity for a chimeric polypeptide provided herein (e.g., a chimeric polypeptide as set forth in any one of FIGS. 2-20 and 23-32) can be generated by known techniques. For example, F(ab′)2 fragments can be produced by pepsin digestion of the antibody molecule, and Fab fragments can be generated by reducing the disulfide bridges of F(ab′)2 fragments. In some cases, Fab expression libraries can be constructed. See, for example, Huse et al., Science, 246:1275 (1989). Once produced, antibodies or fragments thereof can be tested for recognition of a chimeric polypeptide provided herein by standard immunoassay methods including ELISA techniques, radioimmunoassays, and Western blotting. See, Short Protocols in Molecular Biology, Chapter 11, Green Publishing Associates and John Wiley & Sons, Ed. Ausubel et al., 1992.

In immunological assays, an antibody having specific binding affinity for a chimeric polypeptide provided herein or a secondary antibody that binds to such an antibody can be labeled, either directly or indirectly. Suitable labels include, without limitation, radionuclides (e.g., ¹²⁵I, ¹³¹I, ³⁵S, ³H, ³²P, ³³P, or ¹⁴C), fluorescent moieties (e.g., fluorescein, FITC, PerCP, rhodamine, or PE), luminescent moieties (e.g., Qdot™ nanoparticles supplied by Invitrogen (Carlsbad, Calif.)), compounds that absorb light of a defined wavelength, or enzymes (e.g., alkaline phosphatase or horseradish peroxidase). Antibodies can be indirectly labeled by conjugation with biotin then detected with avidin or streptavidin labeled with a molecule described above. Methods of detecting or quantifying a label depend on the nature of the label and are known in the art. Examples of detectors include, without limitation, x-ray film, radioactivity counters, scintillation counters, spectrophotometers, colorimeters, fluorometers, luminometers, and densitometers. Combinations of these approaches (including “multi-layer” assays) familiar to those in the art can be used to enhance the sensitivity of assays.

Immunological assays for detecting a polypeptide provided herein can be performed in a variety of known formats, including sandwich assays, competition assays (competitive MA), or bridge immunoassays. See, for example, U.S. Pat. Nos. 5,296,347; 4,233,402; 4,098,876; and 4,034,074. Methods of detecting a chimeric polypeptide provided herein generally include contacting a biological sample with an antibody that binds to a chimeric polypeptide provided herein and detecting binding of the chimeric polypeptide to the antibody. For example, an antibody having specific binding affinity for a chimeric polypeptide provided herein can be immobilized on a solid substrate by any of a variety of methods known in the art and then exposed to the biological sample. Binding of the chimeric polypeptide to the antibody on the solid substrate can be detected by exploiting the phenomenon of surface plasmon resonance, which results in a change in the intensity of surface plasmon resonance upon binding that can be detected qualitatively or quantitatively by an appropriate instrument, e.g., a Biacore apparatus (Biacore International AB, Rapsgatan, Sweden). In some cases, the antibody can be labeled and detected as described above. A standard curve using known quantities of a chimeric polypeptide provided herein can be generated to aid in the quantitation of the levels of the chimeric polypeptide.

In some embodiments, a “sandwich” assay in which a capture antibody is immobilized on a solid substrate can be used to detect the presence, absence, or level of a chimeric polypeptide provided herein. The solid substrate can be contacted with the biological sample such that any chimeric polypeptide of interest in the sample can bind to the immobilized antibody. The presence, absence, or level of the chimeric polypeptide bound to the antibody can be determined using a “detection” antibody having specific binding affinity for the chimeric polypeptide. In some embodiments, a capture antibody can be used that has binding affinity for ANP, BNP, CNP, DNP, URO, or an angiotensin polypeptide as well as a chimeric polypeptide provided herein. In this embodiment, a detection antibody can be used that has specific binding affinity for a particular chimeric polypeptide provided herein (e.g., a chimeric polypeptide as set forth in any one of FIGS. 2-20 and 23-32). It is understood that in sandwich assays, the capture antibody should not bind to the same epitope (or range of epitopes in the case of a polyclonal antibody) as the detection antibody. Thus, if a monoclonal antibody is used as a capture antibody, the detection antibody can be another monoclonal antibody that binds to an epitope that is either physically separated from or only partially overlaps with the epitope to which the capture monoclonal antibody binds, or a polyclonal antibody that binds to epitopes other than or in addition to that to which the capture monoclonal antibody binds. If a polyclonal antibody is used as a capture antibody, the detection antibody can be either a monoclonal antibody that binds to an epitope that is either physically separated from or partially overlaps with any of the epitopes to which the capture polyclonal antibody binds, or a polyclonal antibody that binds to epitopes other than or in addition to that to which the capture polyclonal antibody binds. Sandwich assays can be performed as sandwich ELISA assays, sandwich Western blotting assays, or sandwich immunomagnetic detection assays.

Suitable solid substrates to which an antibody (e.g., a capture antibody) can be bound include, without limitation, microtiter plates, tubes, membranes such as nylon or nitrocellulose membranes, and beads or particles (e.g., agarose, cellulose, glass, polystyrene, polyacrylamide, magnetic, or magnetizable beads or particles). Magnetic or magnetizable particles can be particularly useful when an automated immunoassay system is used.

Antibodies having specific binding affinity for a chimeric polypeptide provided herein can be produced through standard methods. For example, a chimeric polypeptide can be recombinantly produced as described above or can be chemically synthesized, and used to immunize host animals, including rabbits, chickens, mice, guinea pigs, or rats. For example, a chimeric polypeptide as set forth in any one of FIGS. 2-20 and 23-32 can be used to immunize an animal. Various adjuvants that can be used to increase the immunological response depend on the host species and include Freund's adjuvant (complete and incomplete), mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanin and dinitrophenol. Monoclonal antibodies can be prepared using a chimeric polypeptide provided herein and standard hybridoma technology. In particular, monoclonal antibodies can be obtained by any technique that provides for the production of antibody molecules by continuous cell lines in culture such as described by Kohler et al., Nature, 256:495 (1975), the human B-cell hybridoma technique (Kosbor et al., Immunology Today, 4:72 (1983); Cole et al., Proc. Natl. Acad. Sci. USA, 80:2026 (1983)), and the EBV-hybridoma technique (Cole et al., “Monoclonal Antibodies and Cancer Therapy,” Alan R. Liss, Inc., pp. 77-96 (1983)). Such antibodies can be of any immunoglobulin class including IgG, IgM, IgE, IgA, IgD, and any subclass thereof. The hybridoma producing the monoclonal antibodies can be cultivated in vitro and in vivo.

In some cases, antibodies directed to either an NP sequence or the sequence of an angiotensin polypeptide or a combination of both types of antibodies can be used to detect a chimeric polypeptide provided herein (e.g., a chimeric polypeptide as set forth in any one of FIGS. 2-20 and 23-32).

Other techniques for detecting a chimeric polypeptide provided herein include mass-spectrophotometric techniques such as electrospray ionization (ESI), and matrix-assisted laser desorption-ionization (MALDI). See, for example, Gevaert et al., Electrophoresis, 22:1645-51 (2001); Chaurand et al., J. Am. Soc. Mass Spectrom., 10:91-103 (1999). Mass spectrometers useful for such applications are available from Applied Biosystems (Foster City, Calif.); Bruker Daltronics (Billerica, Mass.); and Amersham Pharmacia (Sunnyvale, Calif.).

Compositions and Methods for Administration

A chimeric polypeptide provided herein (e.g., a chimeric polypeptide as set forth in any one of FIGS. 2-20 and 23-32), or a nucleic acid encoding a chimeric polypeptide provided herein, can be incorporated into a composition for administration to a mammal (e.g., a human suffering from or at risk for AMI or AHF). Methods for formulating and subsequently administering therapeutic compositions are well known to those in the art. Dosages typically are dependent on the responsiveness of the subject to the compound, with the course of treatment lasting from several days to several months, or until a suitable response is achieved. Persons of ordinary skill in the art routinely determine optimum dosages, dosing methodologies, and repetition rates. Optimum dosages can vary depending on the relative potency of a chimeric polypeptide, and generally can be estimated based on the EC₅₀ found to be effective in in vitro and/or in vivo animal models. Compositions containing a chimeric polypeptide provided herein or a nucleic acid provided herein may be given once or more daily, weekly, monthly, or even less often, or can be administered continuously for a period of time (e.g., hours, days, or weeks). For example, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be administered to an myocardial infarction patient at a dose of at least about 0.01 ng polypeptide/kg to about 100 mg polypeptide/kg of body mass at or about the time of reperfusion, or can be administered continuously as an infusion beginning at or about the time of reperfusion and continuing for one to seven days (e.g., at a dose of about 0.01 ng polypeptide/kg/minute to about 0.5 μg polypeptide/kg/minute).

The chimeric polypeptides or nucleic acids can be admixed, encapsulated, conjugated or otherwise associated with other molecules, molecular structures, or mixtures of compounds such as, for example, liposomes, receptor or cell targeted molecules, or oral, topical or other formulations for assisting in uptake, distribution and/or absorption.

In some embodiments, a composition can contain a chimeric polypeptide provided herein in combination with a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers include, for example, pharmaceutically acceptable solvents, suspending agents, or any other pharmacologically inert vehicles for delivering antibodies to a subject. Pharmaceutically acceptable carriers can be liquid or solid, and can be selected with the planned manner of administration in mind so as to provide for the desired bulk, consistency, and other pertinent transport and chemical properties, when combined with one or more therapeutic compounds and any other components of a given pharmaceutical composition. Typical pharmaceutically acceptable carriers include, without limitation: water; saline solution; binding agents (e.g., polyvinylpyrrolidone or hydroxypropyl methylcellulose); fillers (e.g., lactose or dextrose and other sugars, gelatin, or calcium sulfate); lubricants (e.g., starch, polyethylene glycol, or sodium acetate); disintegrates (e.g., starch or sodium starch glycolate); and wetting agents (e.g., sodium lauryl sulfate).

Pharmaceutical compositions containing a chimeric polypeptide provided herein can be administered by a number of methods, depending upon whether local or systemic treatment is desired. Administration can be, for example, parenteral (e.g., by subcutaneous, intrathecal, intraventricular, intramuscular, or intraperitoneal injection, or by intravenous (i.v.) drip); oral; topical (e.g., transdermal, sublingual, ophthalmic, or intranasal); or pulmonary (e.g., by inhalation or insufflation of powders or aerosols), or can occur by a combination of such methods. Administration can be rapid (e.g., by injection) or can occur over a period of time (e.g., by slow infusion or administration of slow release formulations).

Compositions and formulations for parenteral, intrathecal or intraventricular administration include sterile aqueous solutions (e.g., sterile physiological saline), which also can contain buffers, diluents and other suitable additives (e.g., penetration enhancers, carrier compounds and other pharmaceutically acceptable carriers).

Compositions and formulations for oral administration include, for example, powders or granules, suspensions or solutions in water or non-aqueous media, capsules, sachets, or tablets. Such compositions also can incorporate thickeners, flavoring agents, diluents, emulsifiers, dispersing aids, or binders.

Pharmaceutical compositions include, but are not limited to, solutions, emulsions, aqueous suspensions, and liposome-containing formulations. These compositions can be generated from a variety of components that include, for example, preformed liquids, self-emulsifying solids and self-emulsifying semisolids. Emulsion formulations are particularly useful for oral delivery of therapeutic compositions due to their ease of formulation and efficacy of solubilization, absorption, and bioavailability. Liposomes can be particularly useful due to their specificity and the duration of action they offer from the standpoint of drug delivery.

Compositions additionally can contain other adjunct components conventionally found in pharmaceutical compositions. Thus, the compositions also can include compatible, pharmaceutically active materials such as, for example, antipruritics, astringents, local anesthetics or anti-inflammatory agents, or additional materials useful in physically formulating various dosage forms of the compositions, such as dyes, flavoring agents, preservatives, antioxidants, opacifiers, thickening agents, and stabilizers. Furthermore, the composition can be mixed with auxiliary agents, e.g., lubricants, preservatives, stabilizers, wetting agents, emulsifiers, salts for influencing osmotic pressure, buffers, colorings, flavorings, penetration enhancers, and aromatic substances. When added, however, such materials should not unduly interfere with the biological activities of the other components within the compositions (e.g., a chimeric polypeptide provided herein).

In some cases, a chimeric polypeptide provided herein can be formulated as a sustained release dosage form. In some cases, coatings, envelopes, or protective matrices can be formulated to contain one or more of the chimeric polypeptides provided herein. Such coatings, envelopes, and protective matrices can be used to coat indwelling devices such as stents, catheters, and peritoneal dialysis tubing. In some cases, a chimeric polypeptide provided herein can be incorporated into a polymeric substances, liposomes, microemulsions, microparticles, nanoparticles, or waxes.

Pharmaceutical formulations as disclosed herein, which can be presented conveniently in unit dosage form, can be prepared according to conventional techniques well known in the pharmaceutical industry. Such techniques include the step of bringing into association an active ingredient (e.g., a chimeric polypeptide provided herein) with the desired pharmaceutical carrier(s). Typically, the formulations can be prepared by uniformly and intimately bringing an active ingredient into association with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product. Formulations can be sterilized if desired, provided that the method of sterilization does not interfere with the effectiveness of the molecules(s) contained in the formulation (e.g., a chimeric polypeptide provided herein).

Methods for Reducing or Inhibiting Cardiac Remodeling

This document also provides for the use of a chimeric polypeptide provided herein for treatment of, for example, AHF and AMI. For example, a chimeric polypeptide provided herein can be administered to a mammal (e.g., a human or a non-human mammal) in order to reduce or inhibit cardiac remodeling that can occur, for example, after myocardial infarction. In some embodiments, for example, a chimeric polypeptide provided herein or a composition provided herein can be administered to a mammal diagnosed as having had an AMI. The chimeric polypeptide or composition can be administered at any suitable dose, depending on various factors including, without limitation, the agent chosen, the disease, and whether prevention or treatment is to be achieved. Administration can be local or systemic.

In some embodiments, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be administered at a dose of at least about 0.01 ng polypeptide/kg to about 100 mg polypeptide/kg of body mass (e.g., about 10 ng polypeptide/kg to about 50 mg polypeptide/kg, about 20 ng polypeptide/kg to about 10 mg polypeptide/kg, about 0.1 ng polypeptide/kg to about 20 ng polypeptide/kg, about 3 ng polypeptide/kg to about 10 ng polypeptide/kg, or about 50 ng polypeptide/kg to about 100 μg/kg) of body mass, although other dosages also may provide beneficial results. In some cases, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be administered as a continuous intravenous infusion beginning at or about the time of reperfusion (i.e., at the time the occluded artery is opened), and continuing for one to seven days (e.g., one, two, three, four, five, six, or seven days). Such a composition can be administered at a dose of, for example, about 0.1 ng polypeptide/kg/minute to about 500 ng polypeptide/kg/minute (e.g., about 0.5 ng polypeptide/kg/minute, about 1 ng polypeptide/kg/minute, about 2 ng polypeptide/kg/minute, about 3 ng polypeptide/kg/minute, about 5 ng polypeptide/kg/minute, about 7.5 ng polypeptide/kg/minute, about 10 ng polypeptide/kg/minute, about 12.5 ng polypeptide/kg/minute, about 15 ng polypeptide/kg/minute, about 20 ng polypeptide/kg/minute, about 25 ng polypeptide/kg/minute, about 30 ng polypeptide/kg/minute, about 50 ng polypeptide/kg/minute, about 100 ng polypeptide/kg/minute, or about 300 ng polypeptide/kg/minute). In some embodiments, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be administered before reperfusion (e.g., about one hour prior to reperfusion), either as one or more individual doses or as a continuous infusion beginning about one hour prior to reperfusion). For example, a composition can be administered beginning about one hour, about 45 minutes, about 30 minutes, or about 15 minutes prior to reperfusion. In some cases, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be administered after reperfusion (e.g., within about ten hours of reperfusion), and can be administered either as one or more individual doses or as a continuous infusion beginning within about ten hours of reperfusion. For example, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be administered about one hour, about two hours, about three hours, about four hours, about five hours, about six hours, about seven hours, about eight hours, about nine hours, or about ten hours after reperfusion.

In some embodiments, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be administered via a first route (e.g., intravenously) for a first period of time, and then can be administered via another route (e.g., topically or subcutaneously) for a second period of time. For example, a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be intravenously administered to a mammal (e.g., a human) at a dose of about 0.1 ng polypeptide/kg/minute to about 300 ng polypeptide/kg/minute (e.g., about 1 ng polypeptide/kg/minute to about 15 ng polypeptide/kg/minute, about 3 ng polypeptide/kg/minute to about 10 ng polypeptide/kg/minute, or about 10 ng polypeptide/kg/minute to about 30 ng polypeptide/kg/minute) for one to seven days (e.g., one, two, three, four, five, six, or seven days), and subsequently can be subcutaneously administered to the mammal at a dose of about 10 ng polypeptide/kg/day to about 100 ng polypeptide/kg/day (e.g., about 10 ng polypeptide/kg/day, about 20 ng polypeptide/kg/day, about 25 ng polypeptide/kg/day, about 30 ng polypeptide/kg/day, about 50 ng polypeptide/kg/day, or about 100 ng polypeptide/kg/day) for five to 30 days (e.g., seven, 10, 14, 18, 21, 24, or 27 days).

The methods provided herein can include administering to a mammal an effective amount of a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein. As used herein, the term “effective amount” is an amount of a molecule or composition that is sufficient to alter one or more (e.g., one, two, three, four, five, six, seven, eight, nine, or ten) parameters indicative of reduced cardiac remodeling and/or kidney protection in a mammalian recipient by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or 100%). For example, an effective amount of a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein is an amount that can increase ejection fraction, GFR, urinary sodium excretion (UNaV), or urine flow (UV) by at least 10%, and/or that can decrease PRA, LV mass, CF proliferation, PCWP, RAP, MAP, aldosterone levels, LV hypertrophy, ventricular fibrosis, LV end systolic diameter, PFRNa, or DFRNa by at least 10%, and/or that can result in cardiac unloading. In some embodiments, a method can include administering to a mammal an amount of a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein that is sufficient to alter one or more parameters indicative of reduced cardiac remodeling and/or kidney protection by at least 50%.

In some embodiments, for example, an “effective amount” of a chimeric polypeptide provided herein or a composition containing a chimeric polypeptide provided herein can be an amount that reduces PRA and MAP and increases GFR and UV in a treated mammal by at least 10% as compared to the levels of those parameters in the mammal prior to administration of the chimeric polypeptide or composition or without administration of the chimeric polypeptide or composition (e.g., the level of the parameters observed in a previous myocardial infarction episode).

The invention will be further described in the following example, which does not limit the scope of the invention described in the claims.

EXAMPLE Example 1 cANG Induce cGMP Production

cANG was custom-synthesized to have the sequence set forth in FIG. 4 and confirmed by high performance liquid chromatography and mass spectroscopy to have a molecular weight of 3080.6 Da. Human cardiac fibroblasts (CFs; ScienCell, San Diego, Calif.) were cultured in the manufacturer's fibroblast media (ScienCell, San Diego, Calif.) supplemented with fibroblast growth serum (FGS), fetal bovine serum (FBS), and Pen/Strep. Cells were treated at 80-90% confluency. Only cell passages 1 through 4 were used for experiments. To perform a cyclic GMP assay, the cells were treated as described previously (Huntley et al., J. Cell. Physiol., 209(3):943-9 (2006)). Briefly, cells were incubated in Hank's balanced salt solution (Invitrogen, Carlsbad, Calif.) containing 20 mmol/L N-[2-hydroxyethyl]piperazine-N′[2-ethanesulfonic acid], 0.1% bovine serum albumin, and 0.5 mmol/L 3-isobutyl-1-methylzanthine (Sigma, St. Louis, Mo.). Treated cells received 10⁻⁶ M, 10⁻⁸ M, or 10⁻¹⁰ M of NP or cANG for 10 minutes. Cells were lysed in 6% TCA and sonicated for 10 minutes. The samples were ether extracted four times in four volumes of ether, dried, and reconstituted in 500 ml of cGMP assay buffer.

The samples were assayed using a competitive RIA cGMP kit (Perkin-Elmer, Boston, Mass.). Briefly, samples and standards were incubated with 100 mL anti-human cGMP polyclonal antibody and I¹²⁵-antigen for 18 hours. Cyclic GMP assay buffer was added to the samples, and they were centrifuged for 20 minutes at 2500 rpm. The free fraction was aspirated off, and the bound fraction was counted and concentrations determined. Samples were corrected for dilution factors and protein concentration, and values were expressed as pmoles/mL. The assay was highly specific for cGMP, demonstrating no cross-reactivity with ANP, BNP, CNP, and Endothelin-1, and less than 0.001 percent cross-reactivity with cAMP, GMP, GDP, ATP, and GTP.

Like the treatment of CFs with ANP, BNP, and CNP, treatment of CFs with cANG resulted in cGMP production (FIGS. 20 and 21). These results demonstrate that addition of Ang1-7 does not interfere with receptor binding and cGMP generation.

Example 2 BNP-Ang1-7 and Ang1-7BNP Induce cGMP Production

BNP-Ang1-7 and Ang1-7BNP were synthesized to have the sequence set forth in FIG. 3 and FIG. 20, respectively.

HEK 293 cells were stably transfected to express either NPR-A (GC-A) or NPR-B (GC-B) using Lipofectamine (Invitrogen, Grand Island, N.Y.). Transfected cells were maintained in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, 100 U/mL penicillin, 100 U/mL streptomycin, and 250 μg/mL G418. The reagents were obtained from Invitrogen (Grand Island, N.Y.).

The following was performed to carry out cell stimulation and cGMP assays. Cells were plated in 6-well plates and treated as described elsewhere (Tsuruda et al., Circulation Research, 91:1127-1134 (2002)). Briefly, cells were incubated in Hank's balanced salt solution (Invitrogen, Carlsbad, Calif.) containing 20 mmol/L N-[2-hydroxyethyl]piperazine-N′[2-ethanesulfonic acid], 0.1% bovine serum albumin, and 0.5 mmol/L 3-isobutyl-1-methylzanthine (Sigma, St. Louis, Mo.). Treated cells received 10⁻¹⁰ M, 10⁻⁸ M, or 10⁻⁶ M of either BNP-Ang1-7 or Ang1-7BNP for 10 minutes. Cells were lysed in 300 μL 6% TCA and sonicated for 10 minutes. The samples were ether extracted four times in 4 volumes of ether, dried, and reconstituted in 500 μL cGMP assay buffer. The samples were assayed using a competitive MA cGMP kit (Perkin-Elmer, Boston, Mass.) as described elsewhere (Steiner et al., J. Biol. Chem., 247:1106-1113 (1972)). Samples were corrected for dilution factors and protein concentration, and values were expressed as pmol cGMP/well. There was no cross-reactivity with ANP, BNP, CNP, and Endothelin-1, and less than 0.001 percent cross-reactivity with cAMP, GMP, GDP, ATP, and GTP.

Like BNP (FIG. 33A), exposure of NPR-A⁺ HEK 293 cells to either BNP-Ang1-7 or Ang1-7BNP induced cGMP production (FIGS. 33B and 33C). Neither BNP-Ang1-7 nor Ang1-7BNP induced cGMP production in NPR-B⁺ HEK 293 cells (FIGS. 34B and 34C). Minimal cGMP production was observed for NPR-B⁺ HEK 293 cells exposed to BNP (FIG. 34A). Ang1-7 did not induce cGMP production when placed in contact with NPR-A⁺ HEK 293 cells (FIG. 35, left panel) or NPR-B⁺ HEK 293 cells (FIG. 35, right panel).

These results demonstrate that both BNP-Ang1-7 and Ang1-7BNP induce cGMP production. These results also demonstrate that attaching Ang1-7 to a natriuretic polypeptide or a component of a natriuretic polypeptide (e.g., a ring structure of a natriuretic polypeptide) in either an N-terminal location or a C-terminal location does not interfere with the ability of the natriuretic polypeptide or the natriuretic polypeptide component to bind to its natriuretic polypeptide receptor and induce cGMP production.

OTHER EMBODIMENTS

It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. 

What is claimed is:
 1. A polypeptide from 20 to 28 amino acid residues in length, wherein said polypeptide comprises, in an order from amino terminus to carboxy terminus: (a) the sequence set forth in SEQ ID NO: 1 or the sequence set forth in SEQ ID NO: 1 with no more than two additions, deletions, or substitutions, and (b) the sequence set forth in SEQ ID NO:7 or the sequence set forth in SEQ ID NO:7 with no more than five additions, deletions, or substitutions.
 2. The polypeptide of claim 1, wherein said polypeptide comprises the sequence set forth in SEQ ID NO:1.
 3. The polypeptide of claim 1, wherein said polypeptide comprises the sequence set forth in SEQ ID NO:7.
 4. The polypeptide of claim 1, wherein said polypeptide lacks a C-terminal tail attached to a ring structure.
 5. The polypeptide of claim 1, wherein said polypeptide comprises the sequence set forth in SEC) ID NO:34 with no more than five additions, deletions, or substitutions. 